Patent GB-1436361-A (GB)
Title: Laminate structures
IPC: A23L1/00
Filed: 1973-08-17
Abstract: 1436361 Resin laminates; extruding laminates TOYO SEIKAN KAISHA Ltd 17 Aug 1973 [17 Aug 1972 4 Oct 1972 7 July 1973] 39091/73 Headings B5N B5A and B5B [Also in Division B2] A laminate comprises (a) at least one layer comprising a crystalline film-forming polyolefine and/or at least one layer comprising a saponified ethylene-vinyl ester copolymer and (b) at least one layer comprising a blend of (A) a crystalline film-forming polyolefine and (B) a saponified ethylene-vinyl ester copolymer having an ethylene content of 25 to 50 mol per cent and a degree of saponification of at least 96%, the weight ratio of (A) : (B) in said blend being 98 : 2 to 2 : 98, said laminate containing at least one (a) layer bonded directly to a (b) layer. In a preferred embodiment, layer (b) has a stratified structure in which the polymers (A) and (B) are distributed substantially uniformly along the length and the breadth of the layer (b) but non-uniformly through its thickness, in such a manner that the layer (b) contains at least one stratum in which the concentration of the saponified copolymer is at least 1À05X and at least one stratum in which the concentration of the saponified copolymer is 0 to 95X where X is the average concentration of the saponified copolymer in layer (b), the concentrations being expressed as percentages by weight, based on the total weight of (A) + (B). A preferred laminate comprises (a) at least one layer of the polyolefine, (b) at least one layer of the blend and (a<SP>1</SP>) at least one layer of the saponified ethylene-vinyl acetate copolymer, the ratio of the thickness of the layers (a) : (b) : (a<SP>1</SP>) being from 1 : 1 : 1 to 50 : 30 : 1. The saponified ethylene/vinyl ester copolymer may be derived from vinyl acetate, formate or propionate. The polyolefine may be a homo- or co-polymer of an olefine CH 2 =CHR where R is hydrogen or a C 1  to C 4  alkyl group, e.g. polyethylene, polypropylene, an ethylene/propylene copolymer, polybutene-1, polypentene-1, and copolymers of an olefine with vinyl chloride, acrylic acid, methacrylic acid, an acrylate or a methacrylate. In a preferred embodiment, a carbonyl group-containing thermoplastic polymer having 120 to 1400 milliequivalents of carbonyl groups per 100 g. of the thermoplastic polymer is incorporated on the blend layer in an amount of 0À5 to 15 parts by weight per 100 parts by weight of the sum of components (A) and (B) to facilitate melt processing, examples of such polymers being polyacrylic or methacrylic acid esters, ethylene/acrylic acid ester copolymers, acrylic acid ester/acrylic acid copolymers, ethylene/acrylic acid copolymers, styrene/methacrylic acid ester/acrylic acid copolymers, vinyl chloride/acrylate copolymers, vinyl chloride/methacrylate copolymers, styrene/methacrylate/butadiene copolymers, acrylonitrile/methacrylate copolymers, polyvinyl acetate and propionate, copolymers of vinyl acetate with ethylene, an acrylate and vinyl chloride, an ionomeric copolymer, copolymers of maleic anhydride with a vinyl ether, vinyl chloride, ethylene or propylene, polyamides, polyesters, polyureas, polyurethanes, polyureaurethane and polycarbonates. Suitable layer arrangements for the laminates are I(a) blend layer/polyolefine layer, (b) blend layer/saponified copolymer layer; II(a) polyolefine layer/blend layer/polyolefine layer; (b) blend layer/polyolefine layer/blend/ layer; (c) saponified copolymer layer/blend layer/saponified copolymer layer; (d) blend layer saponified copolymer layer/blend layer; III(a) polyolefine layer/blend layer/saponified copolymer layer; (b) two component blend layer/ saponified copolymer layer/three component blend layer; (c) two component blend layer/ polyolefine layer/three component blend layer; and IV polyolefine layer/blend layer/saponified copolymer layer/blend layer/polyolefine layer. The laminates preferably have a thickness of at least 15 Á and up to 6 mm. and may be used in the formation of bottles, tubes, tanks, bags, packaging containers, films or sheets. The laminates may be made by co-extrusion, by simultaneous extrusion of the layers which are brought into contact after extrusion or by extrusion coating. Suitable relationships between temperature, pressure, flow rate and the size of the extrusion passages are given.